With storage systems, a user normally has to initialize a storage volume created in a PC, an external storage device, or the like, before storing data in the storage volume. This initialization is called formatting. In more specific terms, formatting refers to a process of writing in the storage volume initial values of partition information, directory and file names, and configuration information, or patterns that are defined per track and logical sector. Large external storage devices, of which high reliability is demanded, sometimes write a verification code for verifying the integrity of data per logical sector of the storage volume upon formatting.
In recent years, in order to accommodate the explosive increase in the amount of data handled by businesses and users, the capacity of storage media and storage volumes, such as HDDs and the like, has also shown a steady increase. On the other hand, because the rate of increase in such performance as data transfer capability and the like of HDDs has been significantly slower than the rate of increase in storage capacity, the time it takes to format storage volumes keeps increasing. In particular, large external storage devices have to write verification codes with respect to large storage volumes to format them, and thus sometimes take several hours or even several days to format, depending on the capacity of the installed storage device. Consequently, after installing large external storage devices, users sometimes must wait for a while before being able to start using them.
In order to address this problem, such quick formatting techniques as that disclosed in Patent Literature 1, for example, have conventionally been used where a host is able to use a storage volume undergoing formatting without having to wait for completion thereof. According to Patent Literature 1, a storage device executes normal formatting in the background, identifies whether or not a predetermined area in a storage volume is already formatted, and prepares a bitmap for managing the progress of the formatting. Then, in response to an access request from the host, the storage device references the bitmap, determines whether or not the relevant area is already formatted, and makes it possible to execute the access request from the host without having to wait for completion of the formatting by executing the access request if the area is already formatted, or, if the area is not already formatted, executing the access request after a formatting process has been executed with respect to the relevant area. It is noted that in Patent Literature 1, normal formatting is referred to as “sequential formatting,” while the formatting of an area with respect to which an access request from a host is issued is referred to as “quick formatting.” The two will be identified as such in the present specification as well.